Passenger Check-in is the process where travelers confirm their presence on a flight before departure. This can be done online, at a self-service kiosk, or at a check-in counter in the airport. During check-in, passengers provide their identification and flight details, allowing airlines to prepare for boarding. Once checked in, passengers receive a boarding pass, which contains important information such as the flight number, departure time, and gate. Additionally, travelers can check in their luggage during this process, ensuring it is loaded onto the correct flight for their journey.